So, all I want to do is print envelopes through Address Book.app on Mac OS X. I've concluded that it is impossible. I found a way to do it.
I use an HP Laserjet 1300, which allows me to feed it envelopes, but only the thin-side first. Before I upgraded to Leopard, my Macbook Pro printed envelopes just fine (actually, it previewed them in the wrong orientation, but printed them properly). But my Mac Pro has always refused to print them properly. One day, I tried to print a smaller envelope. I chose the smaller envelope size in the print dialog, and SUDDENLY, PRINTING ENVELOPES STOPPED WORKING! No amount of clicking around could restore it to the state it had been in.

To fix the problem I had to choose the orientation to match the screen with the paper feeder. What baffled me is that after the new configuration, the text on the envelope came out rotated 180 degrees from the way it had been printing before. Bizarre.

Then, I upgraded to Leopard. Now, no combination of print orientations works properly. There are a bunch of envelopes strewn about the floor with addresses printed on them in all sorts of weird locations. I think the problem is that the printer driver assumes that the paper is aligned on one side of the paper tray despite the fact that it is actually centered.

I'm so glad I have a Mac. It's so easy to use!

I did a Google search on how to print envelopes with Address Book, and I found about a billion sites with whiny messages like the one you're reading here. I'm going to go try some third-party apps now...